Pressure sensors have become ubiquitous the last several years and have found their way into many applications. These include medical applications, such as respiratory control and sleep-apnea treatment, and industrial applications, such as heating, venting, air conditioning (HVAC) and fire-protection systems.
These pressure sensors are typically formed on a silicon die having a diaphragm over a cavity, where the diaphragm is very thin and is supported by a sidewall or bulk region that forms the cavity. One or more mechanical stress sensors are located on the diaphragm. Pressure, either from above the diaphragm or below the diaphragm in the cavity, deflects the diaphragm and its mechanical stress sensors. From this deflection, pressure can be measured by utilizing the piezo-resistive effect of silicon. That is, as the sensors are stressed due to the bending of the diaphragm, the piezo-resistive effect changes the value of the conductive properties of the stress sensors. This change in conductive properties due to mechanical stress results in a change from which the pressure can be determined.
Unfortunately, conductive properties of the mechanical stress sensors may vary over temperature. Thus, temperature changes may appear as changes in pressure. Because of this, the performance of a pressure sensor may be limited by the ability to determine the temperature influence on its conductive properties.
Thus, what is needed are devices, methods, and systems that enable the measurement of the temperature of a pressure sensor in order to adjust pressure readings generated by the pressure sensor.